1. Field of the Invention
The present invention relates to an image data combining apparatus for combining a plurality of lines of image data that have been output from a reading unit.
2. Description of Related Art
A known method of obtaining image data by reading a document image or the like is to read the image using a line sensor, store the read data in a line memory and subject the data to image processing (e.g., see the specification of U.S. Pat. No. 6,765,703).
Another method known in the art involves dividing sensor pixels, which have been formed on one line, into even- and odd-numbered rows, outputting data, rearranging within the sensor and executing processing of the data as one line of data (e.g., see the specification of U.S. Pat. No. 6,717,617). Thus dividing one line of data from a line sensor and reading out data as a plurality of lines is referred to as “divided readout”. The reason for performing divided readout is to reduce the number of transferred pixels of the line sensor when image data per line is read out, thereby raising readout speed.
In another known arrangement, image data read by scanning a line sensor in the direction in which sensor elements are arrayed (the main-scan direction) is stored in a memory (a band memory) in plural-line units (band units), and the data is then subjected to image processing. Corresponding two-dimensional image portions are developed in the band memory.
Further, the specification of Japanese Patent Laid-Open No. 2006-139606 describes a method of scanning such a band memory in a direction (sub-scan direction) perpendicular to the line, reading out pixel data and executing image processing.
However, in order to deal with the recent demand for higher definition of read images, the number of sensor elements required on one line is increasing and so is the required capacity of the line memory. With the conventional method of using a line memory, apparatus cost rises and the structure of the apparatus is made more complicated by increasing the semiconductor chips used. Further, in the case of the arrangement in which pixels are arrayed in a row within the sensor, as in U.S. Pat. No. 6,717,617, the scale of the sensor itself increases and it is difficult to reduce the size of the apparatus.